In addition to the substances referred to in section 346a(p)(3)(B) of title 21 the Administrator may provide for testing under the screening program authorized by section 346a(p) of title 21 , in accordance with the provisions of section 346a(p) of title 21 , of any other substance that may be found in sources of drinking water if the Administrator determines that a substantial population may be exposed to such substance. (July 1, 1944, ch. 373, title XIV, § 1457, as added Pub. L. 104–182, title I, § 136 , Aug. 6, 1996 , 110 Stat. 1680 .) CFR Title Parts 40 3